Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	$ 81	$ 68
Derivative Asset, Noncurrent	[2]	135	25
Derivative Asset		216	93
Derivative Liabilities, Current		586	408	[3]
Derivative Liabilities, Noncurrent		748	332	[3]
Derivative Liabilities		1,334	740
Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[4]	31	20
Derivative Asset, Noncurrent	[5]	102	4
Derivative Asset		133	24
Derivative Liabilities, Current	[6]	478	243	[7],[8]
Derivative Liabilities, Noncurrent	[9]	526	223
Derivative Liabilities		1,004	466
Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent	[10]		8
Derivative Asset			8
Derivative Liabilities, Current	[11]	76	33
Derivative Liabilities, Noncurrent	[12]	128	53
Derivative Liabilities		204	86
Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		73	67
Derivative Asset, Noncurrent		109	7
Derivative Liabilities, Current		42	83
Derivative Liabilities, Noncurrent		8	48
Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		31	20
Derivative Asset, Noncurrent		102	2
Derivative Liabilities, Current		23	58
Derivative Liabilities, Noncurrent		1	45
Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		8	1
Derivative Asset, Noncurrent		26	10
Derivative Liabilities, Current		539	322
Derivative Liabilities, Noncurrent		733	284
Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			2
Derivative Liabilities, Current		455	185
Derivative Liabilities, Noncurrent		525	178
Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities, Current		71	30
Derivative Liabilities, Noncurrent		121	53
Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		5	3
Derivative Liabilities, Noncurrent		7
Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		5	3
Derivative Liabilities, Noncurrent		7
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	0	31
Derivative Asset, Noncurrent	[2]	0	19
Derivative Asset		0	50
Derivative Liabilities, Current		519	330
Derivative Liabilities, Noncurrent		662	268
Derivative Liabilities		1,181	598
Designated as Hedging Instrument | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[4]	0	0
Derivative Asset, Noncurrent	[5]	0	2
Derivative Asset		0	2
Derivative Liabilities, Current		455	185	[7]
Derivative Liabilities, Noncurrent	[9]	525	178
Derivative Liabilities		980	363
Designated as Hedging Instrument | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent	[10]		8
Derivative Asset			8
Derivative Liabilities, Current	[11]	63	33
Derivative Liabilities, Noncurrent	[12]	128	53
Derivative Liabilities		191	86
Designated as Hedging Instrument | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		0	30
Derivative Asset, Noncurrent		0	1
Derivative Liabilities, Current		0	6
Derivative Liabilities, Noncurrent		0	1
Designated as Hedging Instrument | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		0	0
Derivative Asset, Noncurrent		0	0
Derivative Liabilities, Current		0	0
Derivative Liabilities, Noncurrent		0	0
Designated as Hedging Instrument | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		0	1
Derivative Asset, Noncurrent		0	10
Derivative Liabilities, Current		514	321
Derivative Liabilities, Noncurrent		655	267
Designated as Hedging Instrument | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			2
Derivative Liabilities, Current		455	185
Derivative Liabilities, Noncurrent		525	178
Designated as Hedging Instrument | Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities, Current		58	30
Derivative Liabilities, Noncurrent		121	53
Designated as Hedging Instrument | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		5	3
Derivative Liabilities, Noncurrent		7
Designated as Hedging Instrument | Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		5	3
Derivative Liabilities, Noncurrent		7
Fair Value - Derivatives not under Hedge Accounting
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	81	37
Derivative Asset, Noncurrent	[2]	135	6
Derivative Asset		216	43
Derivative Liabilities, Current		67	78
Derivative Liabilities, Noncurrent		86	64
Derivative Liabilities		153	142
Fair Value - Derivatives not under Hedge Accounting | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[4]	31	20
Derivative Asset, Noncurrent	[5]	102	2
Derivative Asset		133	22
Derivative Liabilities, Current		23	58	[7]
Derivative Liabilities, Noncurrent	[9]	1	45
Derivative Liabilities		24	103
Fair Value - Derivatives not under Hedge Accounting | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent	[10]		0
Derivative Asset			0
Derivative Liabilities, Current	[11]	13	0
Derivative Liabilities, Noncurrent	[12]	0	0
Derivative Liabilities		13	0
Fair Value - Derivatives not under Hedge Accounting | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		73	37
Derivative Asset, Noncurrent		109	6
Derivative Liabilities, Current		42	77
Derivative Liabilities, Noncurrent		8	47
Fair Value - Derivatives not under Hedge Accounting | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		31	20
Derivative Asset, Noncurrent		102	2
Derivative Liabilities, Current		23	58
Derivative Liabilities, Noncurrent		1	45
Fair Value - Derivatives not under Hedge Accounting | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		8	0
Derivative Asset, Noncurrent		26	0
Derivative Liabilities, Current		25	1
Derivative Liabilities, Noncurrent		78	17
Fair Value - Derivatives not under Hedge Accounting | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			0
Derivative Liabilities, Current		0	0
Derivative Liabilities, Noncurrent		0	0
Fair Value - Derivatives not under Hedge Accounting | Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities, Current		13	0
Derivative Liabilities, Noncurrent		0	0
Fair Value - Derivatives not under Hedge Accounting | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			0
Derivative Liabilities, Current		0	0
Derivative Liabilities, Noncurrent		0
Fair Value - Derivatives not under Hedge Accounting | Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			0
Derivative Liabilities, Current		0	$ 0
Derivative Liabilities, Noncurrent		$ 0

[1] Current derivative assets are presented in other current assets in Dominion Energy’s Consolidated Balance Sheets.

[2] Noncurrent derivative assets are presented in other deferred charges and other assets in Dominion Energy’s Consolidated Balance Sheets.

[3] Dominion Energy’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.

[4] Current derivative assets are presented in other current assets in Virginia Power’s Consolidated Balance Sheets.

[5] Noncurrent derivative assets are presented in other deferred charges and other assets in Virginia Power’s Consolidated Balance Sheets.

[6] See Note 19 for amounts attributable to affiliates.

[7] Current derivative liabilities are presented in other current liabilities in Virginia Power’s Consolidated Balance Sheets

[8] Virginia Power’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.

[9] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in Virginia Power’s Consolidated Balance Sheets.

[10] Noncurrent derivatives assets are presented in other deferred charges and other assets in Dominion Energy Gas’ Consolidated Balance Sheets.

[11] Current derivative liabilities are presented in other current liabilities in Dominion Energy Gas’ Consolidated Balance Sheets.

[12] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in Dominion Energy Gas’ Consolidated Balance Sheets.